1. Field of the Invention
The invention generally relates to the field of medical simulators, and more particularly, to the field of birthing simulators.
2. Description of Related Art
Simulators are devices that simulate or mimic the functions or responses of some portion of a natural system. A medical simulator typically simulates the functions or responses of some portion of a human or other animal body. Medical simulators have a variety of uses. For example, they can be used to train medical professionals and paraprofessionals in basic clinical procedures, they can be used by physiologists, engineers, and clinicians in research activities, and they can provide exposure to and training for a number of physiological conditions that are rarely seen in clinical settings. Ultimately, clinicians and researchers are free to practice on—and occasionally fail in their attempts—with a medical simulator, whereas failure in a clinical setting may cause severe harm or death.
Typically, a medical simulator is comprised of some combination of mechanical, electromechanical and, occasionally, software components. The designer of a medical simulator must balance two competing factors, biofidelity and complexity. Stated simply, a simulator that is not faithful to the system that it tries to simulate, and thus cannot produce a realistic simulation, may be of limited use. However, a simulator that is too faithful or too complex can be difficult to construct, difficult to use, and difficult to maintain, all of which detract from the experience of using it. Therefore, a good simulator is faithful enough to include the important functions and structures for the part or system that is being simulated without being so complex as to be burdensome.
Birthing is one physiological process that is useful to simulate, for several reasons. First, while the birthing process itself is a natural process that often concludes without complications, even in an uncomplicated birth, obstetric procedure can cause injury to the fetus and the mother. Moreover, while many births occur without complications, some births do not. Of the different types of complications that may occur, a number of them represent potentially life-threatening obstetric emergencies. Birthing simulators allow clinicians and researchers to research and train for complications and obstetric emergencies without risking fetal or maternal injury.
Shoulder dystocia (SD) is one example of an infrequent and potentially life-threatening birthing complication. In SD, the anterior fetal shoulder is impacted on the maternal symphysis pubis (pubic bone), which impedes the delivery and requires the clinician to perform additional maneuvers to deliver the fetus safely. Potential consequences of improper delivery techniques affect both the mother and the fetus and may range from mild discomfort to fetal paralysis, and in extreme cases, fatality. SD is uncommon; it is reported in only 0.2% to 4% of all vaginal births, although SD may be underreported because the diagnosis is somewhat subjective, since the clinician cannot actually see the shoulder impaction.
Whatever the actual incidence of SD is, because it is uncommon and often unexpected, practicing clinicians only encounter SD infrequently and many have never encountered a case of severe SD, the type of case most likely to be associated with injury. As desirable as it would be to simulate SD and other complicated births, the relative lack of biofidelity in existing birthing simulators makes it difficult to create a realistic simulation that allows clinicians to appreciate the nature of the problem and practice the necessary maneuvers.
The brachial plexus is the main collection of nerve fibers that arise in the upper spine (C5-C8 and T1 vertebrae) and extend into the arm to innervate it. Traumatic injury to the brachial plexus, caused by improper obstetric procedure or excessive traction force during complications like SD, can result in loss of sensation in or paralysis of the arm. However, the brachial plexus is a complex structure that includes multiple nerves branching in different directions; therefore, it can be difficult to predict whether a particular obstetric complication, or the application of a particular level of force, will cause injury to the brachial plexus.